The present invention generally relates to novel surfactant compositions, their preparation and to compositions containing these novel surfactant compositions, together with a pesticide, particularly a herbicide. More particularly, an important aspect of this invention is directed to surfactant compositions having reduced eye irritancy which are useful in the preparation of herbicidal compositions having reduced eye irritation properties in addition to their herbicidal effectiveness. In this regard, a further important aspect of the present invention concerns surfactant compositions which are effective in the formulation of glyphosate-containing herbicidal compositions or pesticidal compositions of other water soluble active ingredients. A method of using the herbicidal compositions is also provided.
Numerous organic pesticides; i.e., chemicals that are useful in the control of bacteria, insects, fungi, weeds and the like, have been developed in recent years. These pesticides, especially herbicides, have found use in agriculture, as well as for household applications. Regardless of whether the pesticide is water soluble or water insoluble, it is desirable to use the same in an aqueous medium rather than in a non-aqueous solvent which is more difficult to use by the formulator and applicator, could cause environmental damage, is more costly and is in general less desirable. Water-based dispersions, emulsions and/or solutions can be prepared from most pesticides using selected surfactants. Proper selection of the surfactant can also improve the efficacy of pesticidal compositions.
Surfactants are useful in the preparation of herbicidal compositions whether the herbicide is water soluble or insoluble. When the herbicide is water insoluble, the surfactant can be used to make a water dispersible herbicide composition. When the herbicide is water soluble, the surfactant can often be used to improve the herbicidal effectiveness of the herbicidal composition.
One class of surfactants that has found success in the preparation of herbicidal compositions includes the polyoxyalkylene alkylamines, such as, for example, ethoxylated tallowamine. These compounds have the necessary surface activity so that many otherwise water insoluble herbicides, as well as water soluble herbicides, can be formulated into concentrates which will form useful dispersions, emulsions and solutions in water. Herbicides formulated into dispersions, emulsions and solutions using these surfactants often have improved herbicidal properties. This class of surfactants is well known to potentiate the herbicidal activity of glyphosate.
While the polyoxyalkylene alkylamine compounds have excellent surfactant properties which often enhance the efficacy of phytotoxicants, they unfortunately are eye irritants and must be used with a high degree of caution.
Reducing or eliminating the eye irritancy of the polyoxyalkylene alkylamine surfactants used with pesticides, without reducing the efficacy of the pesticidal compositions containing the surfactants, is a highly desirable end. The protection of the applicator and personnel preparing the surfactant and pesticidal compositions from eye damage is of paramount importance. Reducing the eye irritancy of the surfactant and pesticidal compositions containing the surfactant, increases the use that can be made of such products while lessening the possibility of injury to personnel handling and using them.
In order to obtain surfactant compositions having the desired characteristics needed for use with the numerous pesticides on the market, various combinations of surfactants have been previously made.
U.S. Pat. No. 4,313,847 describes three component surfactant compositions including a polyoxyalkylene alkyl or alkylaryl ether phosphate ester, a polyoxyalkylene alkylamine and a material selected from the group consisting of nonionic polyoxylated surfactants, polyhydric alcohol esters and polyoxyalkylene glycols. According to this patent, the three component composition is an improved emulsifier enhancing the use of an emulsion containing a water insoluble herbicide.
Combinations of emulsifiers are also shown in the following patents: U.S. Pat. No. 2,872,368 discloses a polyoxyethylene glycol or a polyoxypropylene glycol in combination with an oil soluble alkaline earth metal salt of an alkylated naphthalene sulfonic acid; U.S. Pat. No. 3,683,078 discloses emulsifier compositions having three components: 1) the condensation product of an alkylphenol and an alkylene oxide, 2) a sulfonate salt and 3) a polyoxyalkylene derivative of an alkanol; and U.S. Pat. No. 3,071,550 discloses selected sulfonates in combination with an aliphatic diester of unsaturated carboxylic acids and the condensation product of glycerin and from about 15 to about 27 moles of ethylene oxide.
As stated in British Patent No. 769,736, due to the diverse nature of pesticides, the selection of the proper emulsifying agent in any particular instance is difficult. This patent shows combinations of a surface active alkylaryl polyoxyalkylene glycol ether and a water soluble salt of a phosphate or sulfate ester as one of the ethers. This British patent, like the preceding patents, shows the continuing need for a multitude of surfactants many of which are obtained by combinations of known materials.
It is known to formulate aqueous solutions of the herbicide glyphosate and sulfated nonalkoxylated C.sub.8 -C.sub.10 alkyl alcohol surfactants. Such herbicidal compositions have been sold by Monsanto Company of St. Louis, Mo., for example, under the trademark PONDMASTER.
None of the foregoing patents discusses the problem of surfactants being eye irritants. Yet this is an important factor which must be taken into consideration when preparing and using compositions containing polyoxyalkylene alkylamine surfactants. Thus, there exists an important need for such compositions having reduced eye irritancy without sacrifice of pesticidal activity.
Perhaps the most widely used herbicide worldwide is glyphosate, which chemically is N-phosphonomethylglycine. This product is normally used in an agriculturally acceptable form, such as a water soluble salt; e.g., the isopropylamine salt. For certain commercial uses glyphosate is made into a herbicidal concentrate composition containing a surfactant, which can then be diluted with water for use by the applicator. Often used surfactants for the preparation of these compositions are the aforementioned polyoxyalkylene alkylamines, especially ethoxylated tallowamine. European Patent 290,416 discloses combinations of solubilized glyphosate, equivalent to at least 40 grams per liter of glyphosate acid, and alkoxylated alkylamine surfactants in a ratio of the solubilized glyphosate (expressed as glyphosate acid equivalent) to amine surfactant of from about 1:1.75 to about 6:1. According to this European Patent, the compositions permit a reduction in the surfactant to glyphosate ratio without loss of herbicidal effectiveness. Clearly, the use of compositions containing glyphosate and alkoxylated tallowamine having reduced eye irritation is of considerable importance. The invention described herein presents a method of improving the highly desirable properties of such compositions.
The U.S. Environmental Protection Agency requires that currently commercial aqueous concentrate glyphosate herbicide solutions having an alkoxylated alkylamine surfactant be labelled to contain a precautionary statement that the solution can cause eye burns. To remedy or ameliorate this hazard is a desideratum of long standing.
It is therefore an object of the present invention to provide new compositions containing an alkoxylated alkylamine surfactant.
Another object of the present invention is to provide such surfactant-containing compositions that can be used to prepare pesticidal compositions, particularly herbicidal compositions having significantly reduced eye irritancy.
Another object of the present invention is to provide new methods for the preparation of compositions containing an alkoxylated alkylamine surfactant and having reduced eye irritancy.
Another object of the present invention is to provide compositions of the herbicide glyphosate having agriculturally acceptable herbicidal efficacy and reduced eye irritancy.
Another object of the present invention is to provide new methods for controlling the growth of weeds and other vegetation.
Other objects of the present invention will become apparent from the following description.